I. Technical Field
The present invention relates to a gear pump for an automatic transmission, and more particularly to a gear pump with improved driven gears which reduces manufacturing complexity and eliminates service problems.
II. Discussion
In an automatic transmission, an oil pump is an indispensable element as a source of pressurized oil. The pressurized oil is supplied to a control valve assembly for controlling gear shifting. Commonly, an oil pump comprises a pump housing formed with a circular recess receiving therein pump elements and also includes a pump cover secured to the pump housing to encapsulate the pump elements within the pump housing. The gear pump, itself, generally comprises a drive gear splined to the torque converter input shaft and two driven gears directly engaged to the drive gear. The driven gears are pivotally mounted on pins which are supported by both the pump housing and the pump cover. In operation, rotational energy derived from the torque converter rotates the drive gear which, in turn, rotates the driven gears to cause pressurization of transmission fluid as is known.
Assembly of the above discussed automatic transmission gear pump, however, has some drawbacks. The pins, on which the driven gears are mounted, must be inserted into bores located in the pump housing and pump cover. This requires alignment of each respective bore and the driven gears. Manufacturers, in attempt to achieve this alignment, must maintain tight tolerances in machining the pump housing and cover and must line up the pins with the bores during assembly. This leads to increased manufacturing cost and service problems. The present invention was developed in light of these drawbacks.